Radiocoil



N. MEDVED Sept. lo, 1929.

RADIO COIL Filed April 6, 1926 QN W m m m 3 Patented Sept. 10, 1929.

PATENT OFFICE.

NICHOLAS MEDVED, OF CANTON, OHIO.

RADIOCOIL.

Application led April 6, 1926. Serial No. 100,093.

The invention relates tocoils for use in electrical circuits, and more particularly in radio circuits, in various arrangements such as in a three circuit tuner, or an antenna coil or radio frequency transformer; and the objects of the invention are to provide an improved coil construction which shall have a very limited external magnetic field and will consequently have but little mutual induction with othercircuits, and will not be affected to any great extent by mutual induction from other circuits or sources, and will pick up very few strays or other disturbing fields.

A further object of the invention is to provide an improved radio coil which may be arranged for varying the electrical characteristics, that is to say, the resistance, induction and capacity of a radio circuit as desired; thereby enabling the balancing of the circuits, in for instance, a neutrodyne receiving set, so that signals from a station of a given wave length may always be received by setting the several dials of the set at the same calibrated points on the dial scales.

A further object of the invention is to provide a coil enabling, with a given antenna, a material increase in the wave lengths possible of reception by a given radio set, without switching in or out increases or decreases of antennae, as heretofore required.

These and ancillary objects, which will be apparent to persons skilled in the art of alternating currents and particularly the alternatingv currents used in radio broadcasting and recept-ion, are attained by the use in various arrangements hereinafter set forth ot spirally Wound conical coils.

Several embodiments of the invention are illustrated in the accompanying drawing, forming part hereof, in which Figure 1 is a perspective view of one of t-he improved spirally Wound conical coils;

Fig. 2, an elevation with portions in axial vertical cross section of a plurality of coils arranged for use for example as a variable radio frequency transformer or antenna coil;

' conical surface.

Fig. 3, a side elevation with portions in axial vertical cross section of a plurality of improved coils arranged as a variable three circuit tuner;

Fig-4, a transverse cross section thereof as on line 4 4, Fig. 3; and

Fig. 5, a circuit diagram illustrating the use of the improved coils arranged as the aforesaid three circuit tuner of Figs. 3 and l in a simple radio receiving circuit.

Similar numerals refer to similar parts throughout the drawings.

Referring to Figure 1, a conductor Wire l, is spil-ally wound to form a conical coil 2 including al plurality of successive turns 2 1, 2 2, 2 3, 2 7?, each turn having a ditlerent diameter than the next adjacent turns, and the yplurality of successive turns determining a flaring and preferably The winding of the coil tube is preferably done upon a conical mandrel. After winding the coil upon the mandrel, material such as collodion is applied to structurally secure the turns of the coil to each other and to enable the removal of the spirally wound conical coil from the mandrel without damaging its conical shape.

Such spirally wound conical coils may be formed of wire such as, (l) bare wire, (2) Litzendraugh wire or (3) cotton covered or otherwise insulated wire. In the case of the use of bare wire the coils are wound upon aV threaded conical mandrel so that each coil turn will be spaced, for example if of an inch from the next adjacent turn; and the collodion application is made be-` fore removing the coil from the mandrel and secures the turns of bare wire in the spirally wound conical coil in the .proper position with relation to each other so that there are no short circuits of the coil turns.

In preparing the coils wound from Litzendraugh wire and for cotton covered or f' otherwise insulated Awire it is unnecessary to use a threaded mandrel, the insulation of the wire being sufficient to properly space the coil turns.

ln Fig. 2 a plurality of spirally wound conical coils are arranged for use for ex- 100 ample as a variable radio frequency transformer or antennae coilindicated generally at 3, and including a suitable base 4 preferably made of hard rubber, and provided with an upwardly extending stem 5 terminating in outwardly and upwardly eX- tending spaced arms 6 and 7. Upon the outer end 8 of the arm 6 is mounted a hollow -fconical coil 'support 9l including an outer conical surface 10n and an inner conical surface 11, both-surfaces preferably being coaxial and having the same taper. Through the outer bifurcated end 12 of the arm 7 a threaded and graduated rod 13 extends and is keyed in the arms 12a and 12b of the end 12, and screwed in a nut 14 spaced between the arms 12a and 12, and which nut when rotated causes the threaded rod 13 to move one way or the other through the arms 12a and 12b.

The rod 13 is preferably co-axial with the conical surfaces 10 and 11, and the rod 13 carries upon its inner end 15 a hollow conical coil support 9", havino` inner and outer conical surfaces 10b and 11b preferably geometrically congruent with the surfaces 1OfL and 11a and co-axial therewith, and the surfaces 10a and 10b, and 11 and 11b being preferably concave towards each other, that is to say, the large bases of the conical supports 9u and 9b are adjacent each other between the small bases.

The surfaces 10u and 10b support outer spirally wound conical coils 2a and 2"; while the surfaces 111 and llblmay support inner spirally wound conical coils 2a and 2b constructed according t0 the present invention as heretofore described, and the large bases of the conical coils being adjacent each other between the small bases.

The terminals of the coils may be connected with each other or with associated apparatus in any desired fashion and the effect of the coils upon each other may be varied by rotation of the nut 14 to move the conical support 9b and its conical coils away from or towards the conical support 9a and its conical coils.

In Figs. 3 and 4 are illustrated a plurality of spirally wound conical coils arranged for use for example as a three circuit tunerl indicated generally at 16, and which may include a suitable base 4 preferably made of hard rubber, and provided with an upwardly extending stem 5 terminating in outwardly and upwardly extending spaced arms 6 and 7.

Through the outer bifurcated end 12A of the arm 6 a threaded and graduated rodl 13u extends and is keyed as best illustrated in Fig. 4 in the arms 12Al and 12Ab of the end 12^, and screwed in a nut 143' spaced between one way or the other through the arms 12All and 12A.

Likewise through the outer bifurcated end l2B of the arm 7 a threaded and graduated rod 13J extends and is keyed in the arms 12BEL and 12Bb of the end 12B, and screwed in a nut 14B spaced between the arms 12BB and 12B", and which nut when rotated causes the threaded rod 13b to move one way or the other through the arms 12B and 12H1. y

The rods 13il and 13b are preferably coaxial and carry upon their inner ends 15, and 15b, respectively, hollow conical coil supports 9a and 9b, respectively, having inner and outer conical surfaces 10 and 10b, and 11l and 11b, preferably geometrically congruent with each other, and preferably concave towards each other.

The surfaces 1()a and 10b support outer spirally wound conical coils 2-aand 2b having their large bases adjacent each other between their small bases; while the surfaces 11a and 11b may support inner spirally wound conical coils 2a and 2b similarly arranged and constructed according to the present invention as heretofore described.

Upon a bifurcated upward extension 5 of stem 5, a tickler winding 16 upon a support 16 may be pivotally mounted as by means of a horizontal median shaft 17 extending through the support, and provided at its outer end with a knob 18 for rotating the tickler winding in the bifurcated extension 5.

The tickler winding preferably includes a pair of conical coils 2A and 2B preferably gcometrically congruent with each other, coaxial witli each other, and concave toward each other.

For use in a three circuit tuner in a simple radio receiving circuit the terminals of the coils 2L and 2b, 2a and 2b', and 2A and 2B, may be connected with each other and with associated apparatus as designated in Figs. 3 and 5. In such a circuit arrangement, the connected coils 2n and 2b may be considered a primary winding; the connected coils 2a and 2* may be considered a secondary winding; and the connected coils 2^ and 2lB may be considered a tickler winding; and the connections as illustrated in Figs. 5 are for a well known single tube radio receiving circuit, ordinarily equipped with other types of coils. f f

It is obvious that in such a circuit, rotation of nuts 14a and 14b will vary'the distance between the component coils 2a and 2b of the primary winding, and between the component'coils 2at and 2b of the secondary winding, and will therefore change the characteristicsoffthe circuit thereby enabling .the attainment of the advantages heretofore described.

I claim:

1. Electrical apparatus including a plu-` ralit-y of coils, each coil including a winding having a plurality of turns determining a flaring surface, and having a lar e base and a small base, the large bases of t e coils being adjacent each other between the small bases.

2. Electrical apparatus including a plurality of coils, each coil including a winding having a plurality of turns determining a conical surface, and having a large base and a small base, the large bases of the coils being adjacent each other between the small bases.

3. Electrical apparatus including a plurality of sets of coils, the sets being axially spaced endwise of each other and the coils of each set being stationary with respect to each other, means for moving the sets axially with respect to each other, a coil of one set and a coil of another set being electrically connected with each other and constituting a primary coil, and another coil of one set and another coil of another set being electrically connected with each other and constituting a secondary coil.

4. Electrical apparatus including a plurality of sets of coils, the coils of each set being stationary with respect to each other, means for moving the sets axially with respect to each other, a coil of one set and a coil of another set being electrically connected with each other and constituting a primary coil, and another coil of one set and another coil of another set being electrically connected with each other and constituting a secondary coil, the coils of each set each including a winding having a plurality of turns determining a flaring surface, and having a large base and a small base, the large bases of the coils of one set being adjacent the large bases of the coils of the other set an? between the small bases of the several co1 s.

5. Electrical apparatus including a pluralityof sets of coils, the coils of each set being stationary with respect to each other, means for moving the sets axially with respect to each other, a coil of one set and a coil of another set being electrically connected with each other and constituting a primary coil, and another coil of one set and another coil of another set being electrically connected with each other and constituting a secondary coil, the coils of each set each including a winding having a plurality offturns determining a conical surface, and having a large base and a small base, the large bases of the coils of one set being adjacent the large bases ofthe coils of the other set and between the small bases of the several coils.

In' testimony that I claim the above, I have hereunto subscribed m name.

N ICHOLA MEDVED. 

